A portion of the disclosure of this patent document contains material which is subject to copyright protection. The copyright owner has no objection to the facsimile reproduction by any one of the patent disclosure, as it appears in the U.S. Patent and Trademark Office patent files or records, but otherwise reserves all copyright rights whatsoever.
1. Field of Invention
The field of the present invention relates in general to the field of wireless broadcast of information using one or more multiple access protocols and in particular to methods and apparatus for implementing spatial multiplexing in conjunction with the one or more multiple access protocols during the broadcast of information.
2. Description of the Related Art
In wireless broadcast systems, information generated by a source is transmitted by wireless means to a plurality of receivers within a particular service area. The transmission of such information requires a finite amount of bandwidth, and in current state of the art transmission of information from different sources, must occur in different channels.
Since there are quite a few services (e.g. television, FM radio, private and public mobile communications, etc.) competing for a finite amount of available spectrum, the amount of spectrum which can be allocated to each channel is severely limited. Innovative means for using the available spectrum more efficiently are of great value. In current state of the art systems, such as cellular telephone or broadcast television, a suitably modulated signal is transmitted from a single base station centrally located in the service area or cell and propagated to receiving stations in the service area surrounding the transmitter. The information transmission rate achievable by such broadcast transmission is constrained by the allocated bandwidth. Due to attenuations suffered by signals in wireless propagation, the same frequency channel can be re-used in a different geographical service area or cell. Allowable interference levels determine the minimum separation between base stations using the same channels. What is needed is a way to improve data transfer speed in the multiple access environments currently utilized for wireless communications within the constraints of available bandwidth.
The present invention provides methods and apparatus for implementing spatial multiplexing in conjunction with the one or more multiple access protocols during the broadcast of information in a wireless network.
In an embodiment of the invention, a wireless cellular network for transmitting subscriber datastream(s) to corresponding ones among a plurality of subscriber units located within the cellular network is disclosed. The wireless cellular network includes base stations and a logic. The base stations each include spatially separate transmitters for transmitting in response to control signals and selected substreams of each subscriber datastream on an assigned channel of a multiple access protocol. The logic communicates with each of the base stations. The logic assigns an available channel on which to transmit each subscriber datastream. The logic routes at least a substream of each datastream to at least a selected one of the base stations. The logic also generates control signals to configure at least a selected one of the base stations to transmit the selected substreams to a corresponding one among the plurality of subscriber units on the assigned channel.
In an embodiment of the invention, a subscriber unit for use in a cellular system with base stations, each including spatially separate transmitters for transmitting selected substreams of at least one of a plurality of subscriber downlink datastream(s) on an assigned channel of a multiple access protocol, is disclosed. The subscriber unit includes: spatially separate receivers, a spatial processor, and a combiner. The spatially separate receivers receive the assigned channel composite signals resulting from the spatially separate transmission of the subscriber downlink datastream(s). The spatial processor is configurable response to a control signal transmitted by the base station to separate the composite signals into estimated substreams based on information obtained during the transmission of known data patterns from at least one of the base stations or by using blind training techniques. The spatial processor signals the base stations when a change of a spatial transmission configuration is required in order to resolve the composite signals into estimated downlink datastream(s). The combiner combines the estimated substreams into a corresponding subscriber datastream.
In another embodiment of the invention, a wireless cellular network for transmitting subscriber downlink datastream(s) from a first network to subscribers located within the wireless cellular network is disclosed. The wireless cellular network includes: base stations, subscriber units and a logic. The base stations are each configured for spatially separate transmission of selected substreams of each subscriber downlink datastream on an assigned channel of a multiple access protocol. The subscriber units are each configured for spatially separate reception on the assigned channel of the selected substreams, for combining the substreams into the corresponding subscriber datastream and for initiating a change signal to at least one of the base stations when a change of a spatial transmission configuration is required in order to separate the selected substreams. The logic communicates with each of the base stations and to the first network. The logic is configured to route at least a substream of each subscriber downlink datastream to at least a selected one of the base stations and further configured to vary the routing between a single base station and multiple base stations to vary a spatial transmission configuration of the selected substreams.
In another embodiment of the invention, a wireless cellular network for receiving subscriber datastreams at corresponding ones among a plurality of base stations located within the cellular network is disclosed. The wireless cellular network includes: subscriber units and logic. The subscriber units each include spatially separate transmitters for transmitting, in response to control signals, selected substreams of each subscriber datastream on an assigned channel of a multiple access protocol. The logic communicates with each of the base stations. The logic generates control signals to configure selected ones of the base stations to receive composite signals resulting from the spatially separate transmission of the selected substreams from a corresponding one among the plurality of subscriber units on the assigned channel. The logic also converts the composite signals into estimate substreams and combines the estimated substreams of each subscriber datastream into each subscriber datastream.
In another embodiment of the invention, a wireless cellular network for transmitting subscriber downlink datastream(s) from a first network to subscribers located within the wireless cellular network is disclosed. The wireless cellular network includes base stations and logic. The base stations include at least one transmitter, for transmitting in response to control signals selected substreams of each subscriber datastream on an assigned channel of a multiple access protocol. The logic communicates with each of the base stations. The logic for assigns an available channel on which to transmit each subscriber datastream. The logic routes at least a substream of each datastream to at least a selected one of the base stations. The logic further generates control signals to configure the at least a selected one of the base stations to transmit the selected substreams to a corresponding one among the plurality of subscriber units on the assigned channel.
In an embodiment of the invention, a method for transmitting subscriber downlink datastream(s) from base stations to corresponding ones among a plurality of subscriber units is disclosed. The method includes the acts of:
routing at least a substream of each subscriber downlink datastream to selected one of the base stations;
transmitting the at least a substream of each subscriber downlink datastream from the selected one of the base stations on an assigned channel of a multiple access protocol; and
re-routing at least a substream of each subscriber downlink datastream between a single base station and multiple base stations responsive to a determination that a change of a spatial transmission configuration of the at least a substream of each subscriber downlink datastream signal is required.
In another embodiment of the invention, a method for receiving subscriber downlink datastream(s) transmitted from a plurality of spatially separate transmitters is disclosed. The method includes the acts of:
receiving signals generated from at least one of the plurality of spatially separate transmitters;
determining a number of substreams to be derived from the signals;
separating the signals into the number of substreams determined in said act of determining; and
combining the substreams into a corresponding subscriber downlink datastream.
In another embodiment of the invention, a wireless cellular network for transmitting subscriber datastream(s) to corresponding ones among a plurality of subscriber units located within the cellular network is disclosed. The wireless cellular network includes:
means for routing at least a substream of each subscriber downlink datastream to selected ones of the base stations;
means for transmitting the at least a substream of each subscriber downlink datastream from the selected ones of the base stations on an assigned channel of a multiple access protocol; and
means for re-routing the at least a substream of each subscriber downlink datastream between a single base station and multiple base stations responsive to a signal from a corresponding one of the subscriber units requesting a change of spatial transmission configuration.
In another embodiment of the invention, a subscriber unit for use in a cellular system with base stations each including spatially separate transmitters for transmitting selected substreams of at least one of a plurality of subscriber downlink datastream(s) on an assigned channel of a multiple access protocol is disclosed. The subscriber unit includes:
means for receiving signals generated from at least one of the plurality of spatially separate transmitters;
means for determining a number of substreams to be derived from the signals;
means for separating the signals into the number of substreams determined in said act of determining;
means for combining the substreams into a corresponding subscriber downlink datastream; and
means for signaling the base when a change of a spatial transmission configuration is required in order to resolve the composite signals into estimated substreams.